| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect accumulation of deposits, and to execute burnout processing of the deposits at proper timing on the basis of the detection result, in an exhaust emission control apparatus for an internal combustion engine with a urea selective reduction catalyst.SOLUTION: An exhaust passage 11 of an engine 10 is provided with a urea-based SCR catalyst 12. A branch passage 11a is connected to an exhaust upstream side of the SCR catalyst 12 in the exhaust passage 11. An addition valve 30 for injecting a reducing agent is mounted to an end of the branch passage 11a. The branch passage 11a is provided with a first temperature sensor 41 for detecting deposits accumulated on an inner surface of the branch passage 11a. When the temperature detected by the first temperature sensor 41 indicates a value different from the normal temperature when the accumulation of the deposits is not generated, a control unit 50 determines that the accumulation of the deposit is generated, and executes burnout processing of the deposits. |
